Putative sperm fusion protein IZUMO and the role of N-glycosylation.
IZUMO is the mouse sperm protein proven to be essential for fusion with eggs. It contains one immunoglobulin-like domain with a conserved glycosylation site within. In the present paper, we produced transgenic mouse lines expressing unglycosylated IZUMO (N204Q-IZUMO) in Izumo1 -/- background. The expression of N204Q-IZUMO rescued the infertile phenotype of IZUMO disrupted mice, indicating glycosylation is not essential for fusion-facilitating activity of IZUMO. The N204Q-IZUMO was produced in testis in comparable amounts to wild-type IZUMO, but the amount of N204Q-IZUMO on sperm was significantly decreased by the time sperm reached the cauda epididymis. These data suggest that glycosylation is not essential for the function of IZUMO, but has a role in protecting it from fragmentation in cauda epididymis.
Inoue
Naokazu
N
Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan.
Ikawa
Masahito
M
Okabe
Masaru
M
D000595:Amino Acid Sequence; D000818:Animals; D002459:Cell Fusion; D004285:Dogs; D004822:Epididymis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D005260:Female; D005298:Fertility / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism / Q000502:physiology; D051381:Rats; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology*
D007136:Immunoglobulins; C498177:Izumo1 protein, mouse; D008565:Membrane Proteins